import java.util.LinkedList;
import java.util.Queue;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 25228
 * Date: 2024-08-07
 * Time: 19:14
 */
public class BinaryTree {
    int size=0;

    static class TreeNode {
        public char val;
        public TreeNode left;//左孩子的引用
        public TreeNode right;//右孩子的引用

        public TreeNode(char val) {
            this.val = val;
        }
    }


    /**
     * 创建一棵二叉树 返回这棵树的根节点
     *
     * @return
     */
    public TreeNode createTree() {
        TreeNode a=new TreeNode('a');
        TreeNode b=new TreeNode('b');
        TreeNode c=new TreeNode('c');
        TreeNode d=new TreeNode('d');
        TreeNode e=new TreeNode('e');
        TreeNode f=new TreeNode('f');
        TreeNode g=new TreeNode('g');
        TreeNode h=new TreeNode('h');
        a.left=b;
        a.right=c;
        b.left=d;
        b.right=e;
        c.left=f;
        c.right=g;
        d.left=h;
        return a;
    }

    // 前序遍历
    public void preOrder(TreeNode root) {
        if (root==null){
            return;
        }
        System.out.print(root.val+" ");
        preOrder(root.left);
        preOrder(root.right);
    }

    // 中序遍历
    void inOrder(TreeNode root) {
        if (root==null){
            return;
        }
        preOrder(root.left);
        System.out.print(root.val+" ");
        preOrder(root.right);
    }

    // 后序遍历
    void postOrder(TreeNode root) {
        if (root==null){
            return;
        }
        preOrder(root.left);
        preOrder(root.right);
        System.out.print(root.val+" ");
    }

    public static int nodeSize;

    /**
     * 获取树中节点的个数：遍历思路
     */
    void size(TreeNode root) {
        while (root==null){
            return;
        }
        size(root.left);
        size(root.right);
        size++;
    }

    /**
     * 获取节点的个数：子问题的思路
     *
     * @param root
     * @return
     */
    int size2(TreeNode root) {
        while (root==null){
            return 0;
        }
        return size2(root.left)+size2(root.right)+1;
    }


    /*
     获取叶子节点的个数：遍历思路
     */
    public static int leafSize = 0;

    void getLeafNodeCount1(TreeNode root) {
        if(root==null){
            return;
        }
        if(root.left==null&&root.right==null){
            leafSize++;
        }
        getLeafNodeCount1(root.right);
        getLeafNodeCount1(root.left);
    }

    /*
     获取叶子节点的个数：子问题
     */
    int getLeafNodeCount2(TreeNode root) {
        if(root==null){
            return 0;
        }
        if(root.left==null&&root.right==null){
            return 1;
        }
        return getLeafNodeCount2(root.left)+getLeafNodeCount2(root.right);
    }

    /*
    获取第K层节点的个数
     */
    int getKLevelNodeCount(TreeNode root, int k) {
        if(root==null){
            return 0;
        }
        if(k==1){
            return 1;
        }
        return getKLevelNodeCount(root.left,k-1)+getKLevelNodeCount(root.right, k-1);
    }

    /*
     获取二叉树的高度
     时间复杂度：O(N)
     */
    int getHeight(TreeNode root) {
        if(root==null){
            return 0;
        }
        if(root.left==null&&root.left==null){
            return 1;
        }
        return Math.max(getHeight(root.left),getHeight(root.right))+1;
    }


    // 检测值为value的元素是否存在
    TreeNode find(TreeNode root, char val) {
        if (root==null){
            return null;
        }

        if(root.val==val){
            return root;
        }

        TreeNode leftNode =find(root.left,val);
        if (leftNode!=null){
            return leftNode;
        }

        TreeNode rightNode=find(root.right,val);
        if(rightNode!=null){
            return rightNode;
        }
        return null;
    }
    //层序遍历
    void levelOrder(TreeNode root) {
        if(root==null){
            return;
        }
        Queue<TreeNode> queue=new LinkedList<>();
        queue.offer(root);
        while (!queue.isEmpty()){
            TreeNode cur=queue.poll();
            System.out.print(cur.val+" ");
            if(cur.left!=null){
                queue.offer(cur.left);
            }
            if (cur.right!=null){
                queue.offer(cur.right);
            }
        }
    }


    // 判断一棵树是不是完全二叉树
    boolean isCompleteTree(TreeNode root) {
        if(root==null){
            return true;
        }
        boolean end=false;
        Queue<TreeNode> queue=new LinkedList<>();
        queue.offer(root);
        while (!queue.isEmpty()){
            TreeNode cur=queue.poll();
            if(cur==null){
                end=true;
            }else if(end){
                return false;
            }
            if (cur!=null){
                queue.offer(cur.left);
                queue.offer(cur.right);
            }
        }
        return true;
    }
}